(a) Field of the Invention
The present invention relates to a green light-emitting phosphor for a light-emitting device excited by vacuum ultraviolet rays, a light-emitting device using the same, and a method of preparing the same. More particularly, the present invention relates to a green light-emitting phosphor that is stable with regard to heat, ion bombardment, and vacuum ultraviolet rays, and which has excellent discharging characteristics.
(b) Description of the Related Art
A fluorescent display panel, particularly a plasma display panel, produces a visual display as a consequence of a gas discharge and generation of ultraviolet rays; phosphor excitation; and emission of visual light. Typically, a mixture of Ne and Xe gas is sealed between glass substrates. Electronic excitation (gas discharge) causes the gas mixture to emit vacuum ultraviolet rays (147 nm for Xe), which strike phosphors in the display panel, stimulating then to emit visual light. Phosphors used in other light-emitting devices, such as CRT's and fluorescent lamps, have been studied, and their use in plasma display panels has been considered. To use a phosphor in a plasma display panel, the phosphor must have excellent brightness, luminous efficiency, and color purity, as well as a short decay time, and it must not be easily degraded by heat or ultraviolet rays.
Currently, Zn2SiO4:Mn is the green light-emitting phosphor most commonly used in plasma display panels. Zn2SiO4:Mn has excellent brightness, a long decay time, and quickly saturated brightness when excited by vacuum ultraviolet rays, relative to a blue or red phosphor used in a plasma display panel. However, since Zn2SiO4:Mn has a higher dielectric constant than that of a blue or red phosphor, a higher discharge-inducing voltage is required to drive the plasma display panel. Therefore, green light-emitting phosphors of new compositions that satisfy all requirements of the plasma display panel have been researched.
The phosphors having new compositions typically include BaAl12O19:Mn (see U.S. Pat. Nos. 4,085,351, 5,868,963, and 6,423,248), (Ba, Sr)MgAl14O23:Mn (see EP 0 908 502 A1), and magnetoplumbite (AB12O19)-type phosphors that use Mn as an activator or alkaline earth aluminate having a beta-alumina structure. However, although such phosphors have excellent color purity and decay characteristics relative to the Zn2SiO4:Mn phosphor, they also have low brightness and are more readily degraded by vacuum ultraviolet rays and heat. The result is shorter display life.